Background and purpose: The frequency and pattern of symptomatic recurrence of spontaneous intracranial arterial dissection (IAD) are unknown.
Methods: A follow-up study of 143 patients (85 men, 58 women; mean age, 50.7 [7-83] years) with spontaneous IADs at The University of Tokyo and affiliated hospitals from 1980 to 2000 was conducted. Tissue samples of IAD vessels obtained from 13 patients at various intervals from onset were also examined histologically.
Results: With a mean follow-up of 8.2 years, symptomatic recurrence occurred in 47 patients (33%). Of 37 cases initially presenting with hemorrhage, 35 developed hemorrhagic recurrence with a mean interval of 4.8 days, and 2 developed nonhemorrhagic recurrences after 21 and 85 months, respectively. Of 10 patients initially presenting with nonhemorrhagic symptoms, 1 developed hemorrhagic recurrence 4 days later, and 9 developed nonhemorrhagic recurrences with a mean interval of 8.6 months. Histopathologically, the affected vessels in the acute stage of hemorrhage (days 0-6) demonstrated insufficient granulation formation within the pseudolumen, followed by marked intimal thickening around the pseudolumen and recanalizing vessel formation in the late stage (>day 30). In the late stage of brain ischemia, subintimal and subadventitial hemorrhage accompanied with intimal thickening was observed.
Conclusions: These data indicate that IAD is a disease carrying a relatively high risk of symptomatic recurrence, apparently occurring in 3 phases and patterns: early hemorrhagic recurrence, late nonhemorrhagic recurrence, and chronic fusiform aneurysm transformation. Knowledge of this triphasic recurrence and corresponding histopathological characteristics help determine the treatment and follow-up strategy for IAD patients.